A carpenter's sawing machine disclosed in the Taiwan Pat. 215,621 comprises a base which is provided with a long frame body fastened pivotally therewith. The frame body is provided in two sides thereof with a fastening seat which is in turn provided at the top thereof with two slide rods fastened uprightly therewith. The slide rods are intended to hold a hacksaw. The base is provided at the top thereof with a sectoral recess extending outward at an angle of 90 degrees. The sectoral recess is provided thereon with an angle graduation and in the bottom thereof with a locating hole opposite to the angle cutting line. Located oppositely to the locating hole is an urging rod and a curved rod which is fastened pivotally with the urging rod. The frame body is further provided in the lower end thereof with a pivot serving as a pivoting point of the curved rod, and a spring for confining the curved rod.
The long frame body is provided at both ends thereof with a round shaft sleeve which is provided in the center thereof with a recess of a predetermined depth. The recess is provided with an expanded opening. The recess is further provided in the periphery thereof with a plurality of locating holes. The fastening seat is engaged with a C-shaped ring of the shaft sleeve. The inner diameter of the fastening seat is corresponding to the outer diameter of the shaft sleeve such that their axes are aligned with the cutting bottom line of the hacksaw. The locating hole is further provided with a plurality of locating pin holes in which a locating pin and a spring are disposed pivotally.
As shown in FIG. 1, the hacksaw is provided with a body 10 which is provided at one end thereof with a grip 11, and at other end thereof with an insertion portion 12 for fastening one end of a blade 13. The blade 13 is fastened at other end thereof with the grip 11 by a screw 14.
The prior art sawing machine described above has several drawbacks, which are explicitly described hereinafter.
The curved rod is used to adjust the horizontal cutting angle of the workpiece. The curved rod is engaged in the radial displacement, which is different from the horizontal adjustment of the long frame body. The radial motion is prone to cause the overturn of the whole set of structure and is inconsistent with the inertia motion of the mechanics of the human body.
The longitudinal cutting angle of the workpiece is changed mainly by the outer diametrical rotation of the fastening seat. The shaft sleeve and the fastening seat are pivoted by the locating hole and the locating pin in conjunction with the spring. It requires a precision technique to form a vertical hole along the radial direction in view of the locating hole and the locating being disposed respectively at the radial positions of the shaft sleeve and the fastening seat. As a result, the sawing machine of the prior art is not cost-effective.
The body 10, the insertion portion 12, the grip 11, and the blade 13 are fastened in a "single point" manner such that the blade 13 is prone to become loosened to result in a sawing work of a poor quality.